Common materials for welded pipes are: Q235A, Q235C, Q235B, 16Mn, 20 #, Q345, L245, L290, X42, X46, X60, X80, 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.
The blank used for welded steel pipe is steel plate or strip steel, which is divided into furnace welded pipe, electric resistance welded pipe and automatic arc welded pipe due to different welding processes. Because of its different welding forms, it is divided into two types: straight seam welded pipe and spiral welded pipe. Because of its end shape, it is divided into round welded pipe and special-shaped (square, flat, etc.) welded pipe. Welded pipes are divided into the following varieties due to their different materials and uses:
GB / T3091-2008 (welded steel pipe for low-pressure fluid transportation): mainly used for conveying water, gas, air, oil and heating hot water or steam and other generally low-pressure fluid and other use pipes. Its representative material is: Q235A grade steel.
GB / T14291-2006 (Welding Steel Pipe for Mine Fluid Transportation): Mainly used for straight seam welded steel pipes for mine pressure, drainage and shaft gas discharge. Its representative material is Q235A, B grade steel.
GB / T12770-2002 (stainless steel welded steel pipe for mechanical structure): mainly used for machinery, automobiles, bicycles, furniture, hotel and restaurant decoration and other mechanical parts and structural parts. Its representative materials are 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb and so on.
GB / T12771-1991 (stainless steel welded steel pipe for fluid transportation): mainly used to transport low-pressure corrosive media. Representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc.
In addition, welded stainless steel pipes for decoration (GB / T 18705-2002), welded stainless steel pipes for building decoration (JG / T 3030-1995), and welded steel pipes for heat exchangers (YB4103-2000).
2020年5月6日星期三
Fire prevention measures for seamless steel tube
At present, seamless steel tube construction is increasing, especially in some buildings, the use of seamless steel tube materials is more widespread. Once a fire accident occurs in a building, the fire cannot be extinguished in a short period of time. This requires us to design the building to provide fire protection to the building materials to enhance their fire resistance, and to formulate the necessary emergency plan inside the building to reduce Casualties and property damage. So, what are the fire protection measures for seamless steel tubes?
1. Outer cladding. It is to add an outer cladding on the surface of the seamless steel tube, which can be cast-in-place or sprayed. The cast-in-situ molded solid concrete outer cladding is usually strengthened with steel wire mesh or steel bars to limit shrinkage cracks and ensure the strength of the shell. The spraying method can apply a sand pump to the surface of the seamless steel pipe at the construction site to form a layer. The sand pump can be lime cement or gypsum mortar, or can be mixed with perlite or asbestos. At the same time, the outer cladding can also be made of perlite, asbestos, gypsum or asbestos cement, and light concrete into prefabricated panels, which are fixed on seamless steel pipes with adhesives, nails, and bolts.
2. Fill with water. Straight seam steel pipes are steel pipes with welds parallel to the longitudinal direction of the steel pipe. Usually divided into metric welded steel pipes, welded thin-walled pipes, transformer cooling oil pipes, etc. Straight seam welded pipe production process is simple, high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. It is possible to use narrow blanks to produce welded pipes with larger diameters. It is also possible to use the same width of blanks to produce welded pipes with different pipe diameters. Filling the hollow seamless steel pipe with water is an effective protective measure against fire. This method can keep the seamless steel pipe at a low temperature in the fire, water circulates in the seamless steel pipe, and absorbs the heat of the material itself. The heated water can be recirculated after cooling, or cool water can be introduced through pipes to replace the heated water.
3. Shield. Precision steel pipe is a kind of high-precision steel pipe material processed by cold drawing or hot rolling. Because the inner and outer walls of the precision steel pipe have no oxide layer, withstand high pressure without leakage, high precision, high finish, cold bending without deformation, flaring, flattening and no crack, etc., it is mainly used to produce products for pneumatic or hydraulic components, such as cylinder Cylinders can be seamless or welded. The seamless steel pipe is installed in the wall or ceiling made of refractory materials, or the components are hidden in the gap between the two walls. As long as a little refractory material is added or not added, the purpose of fire prevention can be achieved. This is a very economical method of fire prevention.
4. Expansion materials. The use of seamless steel tube fireproof coating components, this method has the advantages of good fire insulation performance, construction is not limited by the geometric shape of the seamless steel tube, etc., generally do not add auxiliary facilities, and the coating quality is light, and also has a certain decorative effect, It belongs to modern advanced fire prevention technical measures.
http://www.xysteelpipe.com/info/Fire-prevention-measures-for-seamless-steel-tube-1666-1.htm
1. Outer cladding. It is to add an outer cladding on the surface of the seamless steel tube, which can be cast-in-place or sprayed. The cast-in-situ molded solid concrete outer cladding is usually strengthened with steel wire mesh or steel bars to limit shrinkage cracks and ensure the strength of the shell. The spraying method can apply a sand pump to the surface of the seamless steel pipe at the construction site to form a layer. The sand pump can be lime cement or gypsum mortar, or can be mixed with perlite or asbestos. At the same time, the outer cladding can also be made of perlite, asbestos, gypsum or asbestos cement, and light concrete into prefabricated panels, which are fixed on seamless steel pipes with adhesives, nails, and bolts.
2. Fill with water. Straight seam steel pipes are steel pipes with welds parallel to the longitudinal direction of the steel pipe. Usually divided into metric welded steel pipes, welded thin-walled pipes, transformer cooling oil pipes, etc. Straight seam welded pipe production process is simple, high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. It is possible to use narrow blanks to produce welded pipes with larger diameters. It is also possible to use the same width of blanks to produce welded pipes with different pipe diameters. Filling the hollow seamless steel pipe with water is an effective protective measure against fire. This method can keep the seamless steel pipe at a low temperature in the fire, water circulates in the seamless steel pipe, and absorbs the heat of the material itself. The heated water can be recirculated after cooling, or cool water can be introduced through pipes to replace the heated water.
3. Shield. Precision steel pipe is a kind of high-precision steel pipe material processed by cold drawing or hot rolling. Because the inner and outer walls of the precision steel pipe have no oxide layer, withstand high pressure without leakage, high precision, high finish, cold bending without deformation, flaring, flattening and no crack, etc., it is mainly used to produce products for pneumatic or hydraulic components, such as cylinder Cylinders can be seamless or welded. The seamless steel pipe is installed in the wall or ceiling made of refractory materials, or the components are hidden in the gap between the two walls. As long as a little refractory material is added or not added, the purpose of fire prevention can be achieved. This is a very economical method of fire prevention.
4. Expansion materials. The use of seamless steel tube fireproof coating components, this method has the advantages of good fire insulation performance, construction is not limited by the geometric shape of the seamless steel tube, etc., generally do not add auxiliary facilities, and the coating quality is light, and also has a certain decorative effect, It belongs to modern advanced fire prevention technical measures.
http://www.xysteelpipe.com/info/Fire-prevention-measures-for-seamless-steel-tube-1666-1.htm
2020年5月5日星期二
Process characteristics of spiral steel tube
Spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, and urban construction. It is one of the twenty key products developed.
For liquid transportation: water supply and drainage.
For gas transportation: coal gas, steam, liquefied petroleum gas.
For structural use: for piling pipes and bridges; for docks, roads, and building structures.
Main technical characteristics of spiral steel pipe:
1. During the forming process, the steel plate deforms uniformly, the residual stress is small, and the surface is not scratched. The processed spiral steel pipe has more flexibility in the range of diameter and wall thickness. Especially in the production of small and medium-diameter thick-walled pipes, it has advantages that are unmatched by other processes, and can meet the user's more requirements on spiral steel pipe specifications .
2. Adopting advanced double-sided submerged arc welding technology, welding can be achieved in a good position, which is not prone to defects such as misalignment, welding deviation and under-welding, and it is easy to control welding quality.
3, 100% quality inspection of steel pipes, so that the entire process of steel pipe production under effective detection and monitoring, effectively guarantee product quality.
4. All the equipment of the whole production line has the function of networking with computer data acquisition system, real-time data transmission, and the central control room controls the technical parameters in the production process.
5. The raw materials are strip coil, welding wire and flux. Before input, it must undergo strict physical and chemical tests.
6. Strip steel head and tail butt joint, using single wire or double wire submerged arc welding, after coiling into steel pipe, automatic submerged arc welding machine repair welding.
7. Before forming, the strip is subjected to leveling, trimming, planing, surface cleaning and pre-bending.
8. The electric contact pressure gauge is used to control the pressure of the oil cylinder on both sides of the conveyor to ensure the smooth conveyance of the strip.
9.Using external control or internal control roll forming.
10. Weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment and weld gap are strictly controlled.
For liquid transportation: water supply and drainage.
For gas transportation: coal gas, steam, liquefied petroleum gas.
For structural use: for piling pipes and bridges; for docks, roads, and building structures.
Main technical characteristics of spiral steel pipe:
1. During the forming process, the steel plate deforms uniformly, the residual stress is small, and the surface is not scratched. The processed spiral steel pipe has more flexibility in the range of diameter and wall thickness. Especially in the production of small and medium-diameter thick-walled pipes, it has advantages that are unmatched by other processes, and can meet the user's more requirements on spiral steel pipe specifications .
2. Adopting advanced double-sided submerged arc welding technology, welding can be achieved in a good position, which is not prone to defects such as misalignment, welding deviation and under-welding, and it is easy to control welding quality.
3, 100% quality inspection of steel pipes, so that the entire process of steel pipe production under effective detection and monitoring, effectively guarantee product quality.
4. All the equipment of the whole production line has the function of networking with computer data acquisition system, real-time data transmission, and the central control room controls the technical parameters in the production process.
5. The raw materials are strip coil, welding wire and flux. Before input, it must undergo strict physical and chemical tests.
6. Strip steel head and tail butt joint, using single wire or double wire submerged arc welding, after coiling into steel pipe, automatic submerged arc welding machine repair welding.
7. Before forming, the strip is subjected to leveling, trimming, planing, surface cleaning and pre-bending.
8. The electric contact pressure gauge is used to control the pressure of the oil cylinder on both sides of the conveyor to ensure the smooth conveyance of the strip.
9.Using external control or internal control roll forming.
10. Weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment and weld gap are strictly controlled.
2020年4月19日星期日
Causes of oil and gas pipeline leakage
There are many reasons for pipeline leakage, which can be divided into three categories: corrosion perforation, fatigue cracking and external damage.
Although corrosion control measures can significantly reduce corrosion, it does not prevent corrosion. When the cathodic protection is insufficient, the pipeline corrosion process will be slow but will not stop due to cathodic protection; when the cathodic protection is shielded, the pipeline corrosion will not be inhibited at all. Insufficient cathodic protection means that the protection current provided by the cathodic protection system cannot meet the pipeline protection requirements; cathodic protection shielding means that the cathodic protection current is blocked in the flow and cannot reach the predetermined position. When a large area of damage, continuous leakage points or overall insulation performance decline on the coating, it is easy to cause insufficient cathodic protection.
If the oil and gas pipeline is operated under high pressure for a long time, the mechanical properties of the pipeline metal will gradually decay, and the micro-cracks existing in the pipeline weld itself and due to stress corrosion will expand. When the cracks develop to a certain extent, they will cause sudden pipeline rupture accident, leading to leakage. For gas pipelines, pipeline rupture may have catastrophic consequences.
External damage mainly includes natural disasters and human disasters. Floods, landslides, mudslides, and earthquakes can all damage pipelines; human disasters mainly refer to third-party damage, including unintentional damage caused by various construction projects such as road construction and excavation and deliberate damage caused by perpetrators such as drilling holes, stealing oil and gas.
http://www.xysteelpipe.com/info/Causes-of-oil-and-gas-pipeline-leakage-1654-1.htm
Although corrosion control measures can significantly reduce corrosion, it does not prevent corrosion. When the cathodic protection is insufficient, the pipeline corrosion process will be slow but will not stop due to cathodic protection; when the cathodic protection is shielded, the pipeline corrosion will not be inhibited at all. Insufficient cathodic protection means that the protection current provided by the cathodic protection system cannot meet the pipeline protection requirements; cathodic protection shielding means that the cathodic protection current is blocked in the flow and cannot reach the predetermined position. When a large area of damage, continuous leakage points or overall insulation performance decline on the coating, it is easy to cause insufficient cathodic protection.
If the oil and gas pipeline is operated under high pressure for a long time, the mechanical properties of the pipeline metal will gradually decay, and the micro-cracks existing in the pipeline weld itself and due to stress corrosion will expand. When the cracks develop to a certain extent, they will cause sudden pipeline rupture accident, leading to leakage. For gas pipelines, pipeline rupture may have catastrophic consequences.
External damage mainly includes natural disasters and human disasters. Floods, landslides, mudslides, and earthquakes can all damage pipelines; human disasters mainly refer to third-party damage, including unintentional damage caused by various construction projects such as road construction and excavation and deliberate damage caused by perpetrators such as drilling holes, stealing oil and gas.
http://www.xysteelpipe.com/info/Causes-of-oil-and-gas-pipeline-leakage-1654-1.htm
2020年4月16日星期四
ERW, SSAW, LSAW welded steel tube
ERW steel pipe: high-frequency straight seam resistance welded pipe, using hot-rolled wide coil as the material, through pre-bending, continuous forming, welding, heat treatment, sizing, straightening, blocking and other processes, it has a shorter weld seam than the spiral, standard High precision, uniform wall thickness, good surface quality, and high-end benefits under pressure, but the defect is that only small and medium-diameter thin-walled pipes can be produced, and the welds are prone to gray spots, unfused, and groove-shaped corrosion defects. At present, the widely used fields are city gas, crude oil products and oil transportation, etc.
SSAW steel pipe: spiral submerged arc welded pipe, which has a forming angle (adjustable) with the center line of the forming pipe when the pipe is rolled, and is welded while forming, and its welding seam is formed into a spiral line, and the same standard can produce a variety of diameters Standard steel pipe, the material is used to planning larger, the weld can avoid the main stress, the stress is better, the defect is a few standards are poor, the length of the weld is longer than that of the straight pipe, the crack is easy to crack, the slag is included, the welding deviation, etc. Welding defects, welding stress is tensile stress. The general design rules and regulations of long-distance spiral submerged arc for oil and gas pipelines can only be used in category 3 and category 4 areas.
LSAW steel pipe: Straight seam submerged arc welded pipe, which is made of a single medium-thick plate by pressing (rolling) the steel plate in a mold or forming machine, using double-sided submerged arc welding and expanding the diameter to produce. Its product standard planning is wide, and the resistance, plasticity, uniformity and fineness of the weld are good. It has the advantages of large pipe diameter, pipe wall thickness, high pressure resistance, low temperature resistance and corrosion resistance. When creating high-strength, high-endurance, high-quality long-distance oil and gas pipelines, most of the steel pipes required are large-diameter thick-walled straight-seam submerged arcs. According to API standard rules, in large oil and gas transportation pipelines, when passing through Class 1 and Class 2 areas such as the seabed in high cold areas and densely populated urban areas, the straight-seam submerged arc is the only designated pipe type.
SSAW steel pipe: spiral submerged arc welded pipe, which has a forming angle (adjustable) with the center line of the forming pipe when the pipe is rolled, and is welded while forming, and its welding seam is formed into a spiral line, and the same standard can produce a variety of diameters Standard steel pipe, the material is used to planning larger, the weld can avoid the main stress, the stress is better, the defect is a few standards are poor, the length of the weld is longer than that of the straight pipe, the crack is easy to crack, the slag is included, the welding deviation, etc. Welding defects, welding stress is tensile stress. The general design rules and regulations of long-distance spiral submerged arc for oil and gas pipelines can only be used in category 3 and category 4 areas.
LSAW steel pipe: Straight seam submerged arc welded pipe, which is made of a single medium-thick plate by pressing (rolling) the steel plate in a mold or forming machine, using double-sided submerged arc welding and expanding the diameter to produce. Its product standard planning is wide, and the resistance, plasticity, uniformity and fineness of the weld are good. It has the advantages of large pipe diameter, pipe wall thickness, high pressure resistance, low temperature resistance and corrosion resistance. When creating high-strength, high-endurance, high-quality long-distance oil and gas pipelines, most of the steel pipes required are large-diameter thick-walled straight-seam submerged arcs. According to API standard rules, in large oil and gas transportation pipelines, when passing through Class 1 and Class 2 areas such as the seabed in high cold areas and densely populated urban areas, the straight-seam submerged arc is the only designated pipe type.
Disadvantages of Hot Rolled 20 # Straight Seam Steel Pipe
Disadvantages of hot rolled 20 # straight seam steel pipe:
1. Residual stress caused by uneven cooling. Residual stress is the stress of internal self-phase balance without external force. Hot-rolled steel sections of various cross sections have this type of residual stress. The larger the section size of general steel section, the greater the residual stress. Although the residual stress is self-balanced, it still has a certain influence on the performance of the steel member under the action of external forces. Such as deformation, stability, fatigue resistance, etc. may have adverse effects.
2. After welding, the non-metallic inclusions in the straight seam steel pipe are pressed into thin slices, and the delamination phenomenon occurs. The delamination greatly deteriorates the performance of the 20 # straight seam steel tube in the thickness direction, and there may be interlayer tearing when the weld shrinks. The local strain induced by shrinkage of the weld often reaches several times the yield point strain, which is much larger than the strain caused by the load.
Submerged arc welding straight seam steel pipe advantages: it can destroy the casting structure of the steel ingot, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is compact and the mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the 20 # straight seam steel tube is no longer an isotropic body to a certain extent; bubbles, cracks and looseness formed during casting can also be affected by high temperature and pressure Welding.
1. Residual stress caused by uneven cooling. Residual stress is the stress of internal self-phase balance without external force. Hot-rolled steel sections of various cross sections have this type of residual stress. The larger the section size of general steel section, the greater the residual stress. Although the residual stress is self-balanced, it still has a certain influence on the performance of the steel member under the action of external forces. Such as deformation, stability, fatigue resistance, etc. may have adverse effects.
2. After welding, the non-metallic inclusions in the straight seam steel pipe are pressed into thin slices, and the delamination phenomenon occurs. The delamination greatly deteriorates the performance of the 20 # straight seam steel tube in the thickness direction, and there may be interlayer tearing when the weld shrinks. The local strain induced by shrinkage of the weld often reaches several times the yield point strain, which is much larger than the strain caused by the load.
Submerged arc welding straight seam steel pipe advantages: it can destroy the casting structure of the steel ingot, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is compact and the mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the 20 # straight seam steel tube is no longer an isotropic body to a certain extent; bubbles, cracks and looseness formed during casting can also be affected by high temperature and pressure Welding.
The role of oil casing and oil drill pipe
The casing pipe is used to strengthen the well wall, and the inner and outer diameters are much larger than the drill rod; the drill rod is used to connect the drill collar and the drill bit, and the length is sufficient to support the drill bit in the downhole operation. Regardless of function or size, they are all different.
The essence of the casing pipe is:
1. During the drilling process, as the depth of the well increases, the required mud density will increase, and the upper bottom layer may be leaked. The role of the casing is to prevent the upper layer from being leaked when drilling the lower layer.
2. The last oil pipe and tail pipe is the oil passage. The purpose is to stabilize the formation and prevent collapse. If the formation is hard, the well can be completed with open holes.
Open-hole completion can only be applied to a single oil or gas layer with hard and dense rock formations, no water-containing interlayers, and no easy-to-collapse interlayers or some oil and gas layers with the same properties and similar pressures.
http://www.xysteelpipe.com/info/The-role-of-oil-casing-and-oil-drill-pipe-1653-1.htm
The essence of the casing pipe is:
1. During the drilling process, as the depth of the well increases, the required mud density will increase, and the upper bottom layer may be leaked. The role of the casing is to prevent the upper layer from being leaked when drilling the lower layer.
2. The last oil pipe and tail pipe is the oil passage. The purpose is to stabilize the formation and prevent collapse. If the formation is hard, the well can be completed with open holes.
Open-hole completion can only be applied to a single oil or gas layer with hard and dense rock formations, no water-containing interlayers, and no easy-to-collapse interlayers or some oil and gas layers with the same properties and similar pressures.
http://www.xysteelpipe.com/info/The-role-of-oil-casing-and-oil-drill-pipe-1653-1.htm
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